Field of the Invention
The invention generally relates to the simulation of phenomena of the chunks of ice type in the supply of an engine, in particular on the fuel system of the engine.
Description of the Related Art
The fuel system is a portion of the engine comprising, in the direction of the circulation of the fuel, a low-pressure pump that receives fuel coming from a reservoir by the intermediary of a boost pump. At the outlet of the low-pressure pump, the fuel passes through one or several heat exchangers and a main filter, then penetrates into a high-pressure pump designed to inject the fuel into the combustion chamber by the intermediary of suitable injectors and vaporise it in conditions that are conducive to its combustion.
In most countries, this system is highly regulated, in particular at the level of its mechanical resistance.
In particular, the current standards are very demanding with regards to the robustness of the fuel systems faced with the phenomena of freezing and the formation of chunks of ice, in order to attempt to prevent the obstruction by the ice of certain portions of the fuel system such as the heat exchanger.
Icing tests have already been carried out with a device for injecting water into the engine, comprising means adapted to carry out a pre-mixing of water and of fuel in a tank, an injection nozzle, and a regulation system designed to regulate the injection and pre-mixing steps. In order to form an ice slurry (which is a two-phase mixture of aqueous liquid and of ice, comprising both fuel and water in the form of fluid and ice crystals), the injection nozzle comprises a turbulator designed to increase the turbulence of the water before spraying by the injection nozzle into the fuel system.
However, during these tests, the specified concentration does not exceed 300 ppm (parts per million, by volume) in order to provide a homogeneous mixture of the water and of the fuel, and corresponds to the concentrations of water naturally present in the fuel. This is therefore insufficient to simulate a possible detaching of chunks of ice in a fuel system. Moreover, this injection device is well suited for injection times of a few tens of minutes, as the regulation system requires a few seconds in order to start the injection and that the water is injected in several times in very small quantities. However, in order to simulate in particular the detaching of chunks of ice penetrating into the fuel system, it is sought to simulate an injection of the entire volume of water in a very short period of time, of a magnitude of a few seconds, which cannot be obtained with this water injection device. In addition, the flow in the stream of fuel oscillates during the entire duration of the test because the flow rate at the outlet of the nozzle decreases substantially at the time of the water injections. Finally, the recirculation zones created around the injection nozzle and the small size of the water droplets sprayed which are captured by these recirculation zones favour the accumulation of a deposit of ice on the head of the injection nozzle all throughout the test, which, on the one hand risks obstructing the injection nozzle according to the flow rate and the temperature of the water and of the fuel, and on the other hand reduces in an undetermined way and in an undeterminable way the quantity of water that can finally penetrate into the engine.